Such a lighting system is known from European Patent Application EP 482680 A1. A lighting mode of the known lighting system is associated with a certain spatial distribution of the light in the room in which the lighting system is installed. A user of the known lighting system can adapt the illumination of the room in which the lighting system is installed to his activities such as, for example, reading, watching TV, etc, through the choice of a suitable lighting mode. When a certain lighting mode has been set, the tint group of lighting units often supplies a comparatively high luminous flux intended for task lighting at the chosen location, while the luminous fluxes of the other lighting units belonging to a second group supply surround lighting. Often, lighting modes can also be selected attuned to situations in which more than one person uses the room. The different persons will in general perform different tasks in different locations. In such situations, two or more chosen locations are present in the room, a task lighting being realized in each chosen location which suits the task to be performed in this location. It is desirable for the surround lighting to be harmonized with the task lighting so that the overall illumination of the room makes a pleasant impression on the human eye. This harmonization means that the luminous flux of the surround lighting must be chosen within a certain range, which range depends on the luminous flux value(s) in the chosen location(s). The lighting modes, moreover, are programmable in the known lighting system. This renders it possible to program lighting modes for widely differing rooms and for widely differing tasks, the surround lighting being harmonized with the task lighting. This harmonization, however, is lost when a user changes the desired luminous flux value in one or several locations by means of the further adjustment device within a given lighting mode without adapting the luminous flux of the second group of lighting units. This means that one of the main advantages of a lighting system with preprogrammed lighting modes may easily be lost when the system also offers the user the possibility of adjusting the luminous flux for task lighting in accordance with his own preference and/or needs.